Laser device, optical amplifier, optical transmission device, and determination method

Abstract

A laser device includes: a semiconductor laser; a detection circuit which detects optical power in each position of a spot of emission light which is emitted from the semiconductor laser; and a determination circuit which calculates a power distribution of the spot of the emission light and total power of the spot based on the optical power detected by the detection circuit to determine a sudden death failure sign of the semiconductor laser based on the calculated power distribution and the total power.

What is claimed is: 
     
         1 . A laser device comprising:
 a semiconductor laser;   a detection circuit which detects optical power in each position of a spot of emission light which is emitted from the semiconductor laser; and   a determination circuit which calculates a power distribution of the spot of the emission light and total power of the spot based on the optical power detected by the detection circuit to determine a sudden death failure sign of the semiconductor laser based on the calculated power distribution and the total power.   
     
     
         2 . The laser device according to  claim 1 ,
 wherein the determination circuit determines that   there is the sudden death failure sign in the semiconductor laser, in a case where the power distribution satisfies a first condition and the total power satisfies a second condition, and   there is no sudden death failure sign in the semiconductor laser, in a case where the power distribution does not satisfy the first condition or the total power does not satisfy the second condition.   
     
     
         3 . The laser device according to  claim 2 ,
 wherein the determination circuit determines that   there is the sudden death failure sign in the semiconductor laser, in a case where a magnitude of a difference between a feature value of a shape of the power distribution and a first reference value is equal to or greater than a first threshold value and a magnitude of a difference between the total power and a second reference value is less than a second threshold value, and   there is no sudden death failure sign in the semiconductor laser, in a case where the magnitude of the difference between the feature value and the first reference value is less than the first threshold value and the magnitude of the difference between the total power and the second reference value is equal to or greater than the second threshold value.   
     
     
         4 . The laser device according to  claim 3 ,
 wherein the first reference value is an initial value of the feature value, and   the second reference value is an initial value of the total power.   
     
     
         5 . The laser device according to  claim 1 ,
 wherein the power distribution is a two-dimensional power distribution of the spot.   
     
     
         6 . The laser device according to  claim 1 ,
 wherein the detection circuit detects optical power in each position having a pitch narrower than a width of the spot, that is, each position of a region wider than the spot.   
     
     
         7 . The laser device according to  claim 1 , further comprising:
 a plurality of semiconductor lasers,   wherein the detection circuit detects the optical power in each position having the pitch narrower than the width of the spot, that is, each position of a region including the spot of each semiconductor laser,   the determination circuit calculates the power distribution and the total power for each semiconductor laser based on the optical power in each position of the region detected by the detection circuit to determine the sudden death failure sign of each semiconductor laser based on the calculated power distribution and the total power, and   the determination circuit temporarily operates each power distribution through a gauss approximation from a peak position of the optical power in each spot with respect to each spot including a portion where the spots are overlapped with each other among the spots of each of the semiconductor laser, and calculates each power distribution of each of the spots by subtracting the temporarily operated power distributions each other.   
     
     
         8 . The laser device according to  claim 1 ,
 wherein the semiconductor laser is a vertical cavity surface emitting laser,   a ground electrode of the vertical cavity surface emitting laser has an opening for emitting back light which emitted from the vertical cavity surface emitting laser, and   the detection circuit detects optical power in each position of the spot of the back light emitted from the opening.   
     
     
         9 . The laser device according to  claim 8 ,
 a transparent conductive film through which the back light is transmitted is formed on the opening.   
     
     
         10 . The laser device according to  claim 1 ,
 wherein the semiconductor laser is a vertical cavity surface emitting laser,   a ground electrode of the vertical cavity surface emitting laser is formed by a transparent conductive film through which the back light of the vertical cavity surface emitting laser is transmitted, and   the detection circuit detects optical power in each position of the spot of the back light emitted from the ground electrode.   
     
     
         11 . The laser device according to  claim 1 ,
 wherein the detection circuit is a plurality of photo detectors arranged two dimensionally.   
     
     
         12 . The laser device according to  claim 1 ,
 wherein the determination circuit determines the sudden death failure sign of the semiconductor laser based on at least one of a spread of the power distribution of the spot of the emission light and a change in the number of peaks of the power distribution of the spot of the emission light.   
     
     
         13 . An optical amplifier comprising:
 a semiconductor laser;   an optical amplification medium which allows incident light and emission light emitted from the semiconductor laser to be passed to amplify and emit the incident light;   a detection circuit which detects optical power in each position of a spot of the emission light; and   a determination circuit which calculates a power distribution of the spot of the emission light and total power of the spot based on the optical power detected by the detection circuit to determine a sudden death failure sign of the semiconductor laser based on the calculated power distribution and the total power.   
     
     
         14 . An optical amplifier comprising:
 a semiconductor optical amplifier;   a detection circuit which detects optical power in each position of a spot of emission light which is emitted from the semiconductor optical amplifier; and   a determination circuit which calculates a power distribution of the spot of the emission light and total power of the spot based on the optical power detected by the detection circuit to determine a sudden death failure sign of the semiconductor optical amplifier based on the calculated power distribution and the total power.   
     
     
         15 . The optical amplifier according to  claim 14 ,
 wherein the emission light is an amplified spontaneous emission light emitted from the semiconductor optical amplifier.   
     
     
         16 . An optical transmission device comprising:
 a semiconductor laser which emits an optical signal based on an input data signal;   a detection circuit which detects optical power in each position of a spot of emission light which is emitted from the semiconductor laser; and   a determination circuit which calculates a power distribution of the spot of the emission light and total power of the spot based on the optical power detected by the detection circuit to determine a sudden death failure sign of the semiconductor laser based on the calculated power distribution and the total power.   
     
     
         17 . A determination method for determining a sudden death failure sign of a semiconductor laser or a semiconductor optical amplifier, the method comprising:
 detecting optical power in each position of a spot of emission light which is emitted from the semiconductor laser or the semiconductor optical amplifier;   calculating a power distribution of the spot of the emission light and total power of the spot based on the detected optical power; and   determining the sudden death failure sign of the semiconductor laser or the semiconductor optical amplifier based on the calculated power distribution and the total power.